programming-for-dummies

108
Software Engineering Methods
Software Engineering Methods
In the early days of computer programming, a single programming genius
might create a program. However, relying on the inspiration and creativity of
a single genius isn’t a way to run a business. If the programming genius dies
or quits, the company selling that program won’t know how to fix or update
the program later.
So the idea behind software engineering is to remove a company’s dependence
on a single programming genius and establish a systematic method for
creating software that can be done with an army of competent programmers
rather than a single inspired programming wizard.
Over the years, computer scientists have created a variety of software engineering
methods, which all have advantages and disadvantages. No matter
which software engineering method is popular today or tomorrow, the goals
are always the same:
✦ Make it easy to write large computer programs within a reasonable
period of time.
✦ Create software that works reliably.
Writing large programs is hard enough. Being able to create large programs
within a strict deadline is much harder and making sure the software can be
trusted to work reliably is even tougher. Software engineering methods try to
solve these problems in various ways with different results, ranging from
complete success (rare) to abysmal failures (more common than you might
like to think).
Designing a program with the waterfall model
The waterfall model of software engineering divides the task of creating a
large software project into distinct parts with each part being fully completed
before the other part can even begin.
Typically, the waterfall method divides a software project into four parts, as
shown in Figure 5-1:
✦ Analysis
✦ Design
✦ Implementation
✦ Testing
The idea behind the waterfall method is to complete tasks one at a time so
that you’re always focusing on a single task.